Plasma immersion ion implantation of a semiconductor wafer is typically used to form P—N junctions in the wafer surface. The plasma immersion ion implantation (P3i) process is faster or more productive than other implantation processes. In order to attain a requisite implantation or junction depth, ion energy at the wafer surface must relatively high, which can be accomplished by applying a sufficiently high RF bias power to the wafer, or to an electrode within the wafer support pedestal. The P3i reactor chamber is typically constructed of aluminum components whose surfaces are anodized to provide some protection and from plasma in the chamber. One problem is that the high ion energy of the plasma during ion implantation produces ion bombardment of the metallic chamber components, removing metal particles that vaporize into the plasma to spread throughout the chamber and deposit on the wafer. The high ion energy is attained by coupling RF bias power to the wafer at a sufficient level to create a plasma bias voltage on the order of tens or hundreds of kilovolts. Such metal contamination of the wafer can produce defects in the devices formed on the wafer surface.